1. Technical Field
This invention relates to an assembling method for forming a bead assembly for automobile tires which consists of a bead ring, a bead filler, a bead flipper and a side ply, an assembling apparatus therefor, and a bead filler/bead ring subassembly forming apparatus.
2. Technical Background
A bead assembly for automobiles tires is known, which, as shown in FIG. 26, comprises a wedge-shaped bead filler 2 bonded to the outer peripheral surface of a bead ring 1, a flipper 3 covering the bonded region from inside, and a side ply 4 bonded to the outer lateral surface of the flipper 3. And an example of an apparatus for joining the bead filler 2 to the outer peripheral surface of said bead ring 1 is described in Japanese Patent Publication No. 51540/1986. This apparatus, as shown in FIG. 27 in the present application, comprises a bead driving drum 5 having a groove 5a on the outer periphery, and a pair of dish-shaped pressing disks 6, with the bead ring 1 being fitted in the groove 5a of the bead driving drum 5 to be thereby rotated while the bead filler 2 is tangentially fed to the outer periphery of the bead ring 1, so that the bead filler 2 is nipped between the pressing disks 6 which press the bead filler 2 therebetween.
An example of an apparatus for assembling the bead filler/bead ring subassembly, the bead flipper 3 and the side ply 4 is shown in Japanese Patent Publication No. 18240/1972. This apparatus comprises a pair of turn-up bladders axially juxtaposed for contact with the outer periphery of a cylindrical drum, and bell-shaped frames disposed on opposite sides of the cylindrical drum. In operation, the flipper is wound around the turn-up bladders, followed by the side ply being wound around one side of the flipper, whereupon the pair of turn-up bladders are inflated to raise the flipper on one side and the flipper on the opposite side and the side ply so as to press the flipper on one side against one side of the bead filler while pressing the other flipper on the opposite side together with the side ply against the opposite side of the bead filler. And in this state, the frames on opposite sides are moved forward to nip the turn-up bladders under pressure, thereby pressing the flipper and side ply strongly against the bead filler/bead ring subassembly to connect them together.
Since the bead filler 2 is produced in the form of a strip of wedge-shaped cross section, the bead filler 2 is bent with its thick-walled base portion directed inward when the thick-walled side edge of the bead filler 2 is bonded to the outer peripheral surface of the bead ring 1. As a result, the base portion is compressed in the direction of the length (which is perpendicular to the paper surface of FIG. 27) while the front edge of the opposite thin-walled side is elongated in the direction of the length. Recently, there has come to be used a high bead filler which is a modification of the bead filler 2 made by considerably increasing its width B as compared with its thickness t. In the case of the high bead filler, the elongation of the front edge portion increases until it can hardly be elongated any more, thus presenting the problem of the so-called end gapping which defines a triangular gap between the opposite ends of the bead filler 2 when the latter has been wound a complete turn around the outer periphery of the bead ring 1.
Further, according to the method of assembling the bead ring, bead filler, flipper and side ply as described in the aforementioned Japanese Patent Publication No. 18240/1972, since the flipper extending in opposite directions from the fitted region of the bead ring is bent by inflating the turn-up bladders and since the exhaust is effected by the self contraction of the turn-up bladders, the operation takes a long time and can hardly be automated.
This invention provides a method of automatically assembling the bead ring, bead filler, flipper and side ply, which method eliminates the aforementioned end gapping, an assembling apparatus suitable for use in the method, and a bead filler/bead ring subassembly forming apparatus.